fixed extendComponent()

components.js

function extendComponent(constructor) {
  // Don't do anything if the constructor already extends Component
  if (constructor.prototype instanceof Component)
    return;

  // Otherwise, add an instance of Component to its prototype chain
  var c = constructor.prototype;
  for (var p = Object.getPrototypeOf(c); p !== Object.prototype && p !== Function.prototype; p = Object.getPrototypeOf(c)) {
    c = p;
  }

  Object.setPrototypeOf(c, Component.prototype);
}